Boeing said New Delhi-based SpiceJet ordered 10 of the short- to medium-range 737-800s, valued at more than $700 million at list prices. Airlines often negotiate discounts to the list price.

SpiceJet previously ordered 20 of the 737s.

"These aircraft are enabling us to add capacity on new and existing routes, and will continue to support SpiceJet's mission of being India's preferred low-cost airline," said Bhulo Kansagra, a director on SpiceJet's board.

Russia's S7 Airlines, formerly Sibir, said it ordered 10 of Boeing's 737-800s to expand its charter fleet. The company also said it has rights to purchase

10 more. The planes have a catalog price of about $700 million.

"This large contract with Boeing is a major event for us and allows us to look with optimism at resolving one of S7's most important tasks -- creating a new, modern fleet in the next seven years," company general director Vladislav Filyov said in a statement.